Dimensional analysis: a magic art in fire research?

Thomas, P.H.

doi:10.1016/s0379-7112(99)00054-5

Cited by 16 publications

(7 citation statements)

References 13 publications

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“…Thomas [25] discussed certain examples critically and commented on the analysis of experimental data in the context of dimensional analysis. Dimensional analysis was performed to acquire the law of maximum smoke temperature along the corridor.…”

Section: Dimensional Analysismentioning

confidence: 99%

Scaled Experimental Study on Maximum Smoke Temperature along Corridors Subject to Room Fires

et al. 2015

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Abstract:In room-corridor building geometry, the corridor smoke temperature is of great importance to fire protection engineering as indoor fires occur. Theoretical analysis and a set of reduced-scale model experiments were performed, and a virtual fire model was proposed, to investigate the correlations between the maximum smoke temperature in corridors and the smoke temperature in rooms. The results show that the dimensionless virtual fire heat release rate (HRR) is characterized by quadratic-polynomial of the dimensionless smoke temperature in fire rooms. The dimensionless distance from a virtual fire source to the corridor ceiling varies linearly with the dimensionless smoke temperature in a room. Results of multiple regression indicate that, at the impingement area of virtual fire, the dimensionless maximum smoke temperature in corridors is only related to the dimensionless virtual fire HRR; in the non-impingement area of a virtual fire, the dimensionless maximum smoke temperature in corridors is a function of the dimensionless virtual fire HRR and dimensionless longitude distance. The viscosity and conduction exhibit an insignificant impact on the maximum temperature in the corridor. Through replacing the parameters of virtual fire with the dimensionless smoke temperature in fire rooms, the correlations between dimensionless maximum temperature in corridors and the dimensionless smoke temperature in fire rooms were proposed. OPEN ACCESSSustainability 2015, 7 11191

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Section: Dimensional Analysismentioning

confidence: 99%

Scaled Experimental Study on Maximum Smoke Temperature along Corridors Subject to Room Fires

et al. 2015

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“…Quintiere [6] examined the principles for scaling fire phenomena from dimensionless groups derived from governing differential equations. Thomas [7] pointed out that scaling in fire is an art of selecting the proper groups to characterize the fire. Scaling laws derived from dimensionless numbers can be easily used to translate the results from a model fire experiment into a full-scale system.…”

Section: Introductionmentioning

confidence: 99%

Verification of Similarity of Scaling Laws in Tunnel Fires with Natural Ventilation

et al. 2021

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Scaling laws based on the conservation of the Froude number have been widely used in both fire research and fire engineering design in tunnels. However, the applicability of scaling laws in tunnel fires with natural ventilation has not been systematically verified. In order to verify the scaling laws for tunnel fires with natural ventilation, two model tunnels were tested: Tunnel-L, measuring 20 m long, 0.9 m wide and 0.46 m high, representing the prototype tunnel, and Tunnel-S, measuring 10 m long, 0.45 m wide and 0.23 m high, representing a ½-reduced-scale tunnel. Both tunnels were made of material with a very low heat transfer coefficient, thus heat loss at the boundaries was negligible. The first series of fire tests, with heat release rates of 15.8 kW, 31.6 kW and 63.2 kW, was conducted in Tunnel-L and the second series of fire tests, with heat release rates of 2.8 kW, 5.6 kW and 11.2 kW, was conducted in Tunnel-S. The experimental results showed that compared to the physically measured data in Tunnel-L, the data deduced from Tunnel-S based on scaling laws could lead to a significant under-estimation of the peak temperature rises along the tunnel with errors as high as 50 $ 70%, except those above the fire sources, and a remarkable over-estimation of smoke concentrations. The study demonstrated that scaling laws could be invalid for tunnel fires with natural ventilation and that results measured in reduced-scale tunnels should be further verified when applied to full-scale prototypes.

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“…There are analyses [6] that prove that in fire-related flows, one should preserve the Froude-number, not the Reynolds number when scaling is applied. In this case, so-called partial scaling is adopted that favors the Fr over the Re [7]. Quintiere et al mentioned that maintaining sufficient height of the scale model compartment (>0.3 m) may be adequate to maintain flow turbulence [5].…”

Section: Introductionmentioning

confidence: 99%

“…Heat Release Rate measurements in the performed experiments-moving averages (5 s averaging time) calculated from mass loss measurements. Values measured in reduced-scale were scaled up based on Equations (6) and(7).…”

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confidence: 99%

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Several Problems with Froude-Number Based Scale Modeling of Fires in Small Compartments

et al. 2019

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The Froude-number based reduced-scale modeling is a technique commonly used to investigate the flow of heat and mass in building fires. The root of the method is the thermodynamic model of a flow in a compartment and several non-dimensional flow numbers based on the proportionalities of the Navier-Stokes and heat transfer equations. The ratio of inertial forces to the buoyancy forces, known as the Froude-number, plays a pivotal role within these proportionalities. This paper is an attempt to define the range of credible scale modeling using the Froude-number. We verify the credibility of the modeling by small fire (approximately 150 kW) in a small compartment, comparing data from a physical test (scale 1:1 and 1:4) and the numerical model’s data (Fire Dynamics Simulator, scales 1:1, 1:2, 1:4, 1:10, 1:20, and 1:50). The scope of the research covers a wide range of fires, with observed change of the flow from turbulent to laminar. The results show that the applicability of Froude-number reduced-scale modeling has limitations related to the scale. Therefore, it should be applied with care following sensibility analysis. We propose a method for sensibility analysis using Computational Fluid Dynamics (CFD) modeling.

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Dimensional analysis: a magic art in fire research?

Cited by 16 publications

References 13 publications

Scaled Experimental Study on Maximum Smoke Temperature along Corridors Subject to Room Fires

Scaled Experimental Study on Maximum Smoke Temperature along Corridors Subject to Room Fires

Verification of Similarity of Scaling Laws in Tunnel Fires with Natural Ventilation

Several Problems with Froude-Number Based Scale Modeling of Fires in Small Compartments

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